World of Swift operators

This is all about how to work with operators in Swift, how to declare custom ones and the main thing, that we don’t have to be afraid to see them and to use them.

Transcript

1. WORLD OF SWIFT OPERATORS © Dmitrii Celpan, mobOS 2017
2. SHORT STORY © Dmitrii Celpan, mobOS 2017
3. OBJECTIVE-C -> SWIFT © Dmitrii Celpan, mobOS 2017
4. @objc protocol ObjectiveCProtocol { optional func someOptionalFunct() } class SomeProcessor: NSObject, ObjectiveCProtocol { func processSomething(inout something: [String: AnyObject]) { // some Objective-C like code something = [:] } override class func initialize() { // some awful stuff } } © Dmitrii Celpan, mobOS 2017
5. SWIFT 2.X © Dmitrii Celpan, mobOS 2017
6. extension Employee: Decodable { static func decode(json: JSON) -> Decoded<Employee> { return curry(Employee.init) <^> json <| "id" <*> json <| "name" <*> json <|? "email" <*> json <| ["department", "name"] <*> json <|| "projects" } } © Dmitrii Celpan, mobOS 2017
7. !!! extension Employee: Decodable { static func decode(json: JSON) -> Decoded<Employee> { return curry(Employee.init) <^> json <| "id" <*> json <| "name" <*> json <|? "email" <*> json <| ["department", "name"] <*> json <|| "projects" } } © Dmitrii Celpan, mobOS 2017
8. A BRIEF LOOK AT THE WORLD OF SWIFT OPERATORS © Dmitrii Celpan, mobOS 2017
9. PREFIX OPERATOR prefix operator =/ prefix func =/ (string: String) -> String { return "!, " + string } print(=/"not sure") // "!, not sure" © Dmitrii Celpan, mobOS 2017
10. POSTFIX OPERATOR postfix operator ^^ postfix func ^^ (string: String) -> String { return string + " !" } print("Pretty nice"^^) // "Pretty nice !" © Dmitrii Celpan, mobOS 2017
11. SWIFT OPERATORS postfix operator .> postfix func .> <T>(value: T) { print(value) } "print me".> // "print me" © Dmitrii Celpan, mobOS 2017
12. INFIX OPERATOR infix operator ?? : NilCoalescingPrecedence infix operator ..< : RangeFormationPrecedence infix operator ... : RangeFormationPrecedence infix operator + : AdditionPrecedence infix operator - : AdditionPrecedence infix operator * : MultiplicationPrecedence infix operator / : MultiplicationPrecedence [and many more] © Dmitrii Celpan, mobOS 2017
13. INFIX OPERATOR infix operator ?? : NilCoalescingPrecedence public func ?? <T>(optionalValue: T?, value: T) -> T { guard let unwrapedValue = optionalValue else { return value } return unwrapedValue } © Dmitrii Celpan, mobOS 2017
14. PRECEDENCE GROUP © Dmitrii Celpan, mobOS 2017
15. PRECEDENCE GROUP MultiplicationPrecedence > AdditionPrecedence NilCoalescingPrecedence > ComparisonPrecedence © Dmitrii Celpan, mobOS 2017
16. POPULAR CUSTOM OPERATORS IN SWIFT © Dmitrii Celpan, mobOS 2017
17. PIPELINE OPERATOR infix operator |> : PipelineLeftPrecedence public func |> <T, U>(x: T, f: (T) -> U) -> U { return f(x) } infix operator <| : PipelineRightPrecedence public func <| <T, U>(f: (T) -> U, x: T) -> U { return f(x) } © Dmitrii Celpan, mobOS 2017
18. PIPELINE OPERATOR let intToDouble: (Int) -> Double = { Double($0) } let doubleToString: (Double) -> String = { String($0) } let parameter = 3 let someString = doubleToString(intToDouble(parameter)) © Dmitrii Celpan, mobOS 2017
19. PIPELINE OPERATOR let intToDouble: (Int) -> Double = { Double($0) } let doubleToString: (Double) -> String = { String($0) } let parameter = 3 //let someString = doubleToString(intToDouble(parameter)) let someString1 = parameter |> intToDouble |> doubleToString © Dmitrii Celpan, mobOS 2017
20. FUNCTION COMPOSITION OPERATOR precedencegroup FunctionCompositionPrecedence { associativity: left higherThan: MultiplicationPrecedence } infix operator >>> : FunctionCompositionPrecedence public func >>> <A, B, C>(f: @escaping (A) -> B, g: @escaping (B) -> C) -> (A) -> C { return { x in g(f(x)) } } © Dmitrii Celpan, mobOS 2017
21. FUNCTION COMPOSITION OPERATOR let managedObjectToModel: (NSManagedObject) -> Model let modelToDictionary: (Model) -> Dictionary let managedObjectToDictionary = managedObjectToModel >>> modelToDictionary © Dmitrii Celpan, mobOS 2017
22. OPTIONAL+APPLICATIVE OPERATOR precedencegroup ApplicativePrecedence { associativity: left lowerThan: NilCoalescingPrecedence } infix operator <*> : ApplicativePrecedence public func <*> <T, U>(f: ((T) -> U)?, a: T?) -> U? { return f.flatMap { a.map($0) } } © Dmitrii Celpan, mobOS 2017
23. OPTIONAL+APPLICATIVE OPERATOR let optionalValue: String? = "someString" let optionalFunction: ((String) -> Void)? = { print($0) } guard let value = optionalValue, let function = optionalFunction else { return } function(value) © Dmitrii Celpan, mobOS 2017
24. OPTIONAL+APPLICATIVE OPERATOR let optionalValue: String? = "someString" let optionalFunction: ((String) -> Void)? = { print($0) } //guard let value = optionalValue, // let function = optionalFunction else { // return //} //function(value) optionalFunction <*> optionalValue © Dmitrii Celpan, mobOS 2017
25. ARE THE OPERATORS REALLY THAT GREAT? OR NOT? ! © Dmitrii Celpan, mobOS 2017
26. THINGS TO REMEMBER > Documentation is a must © Dmitrii Celpan, mobOS 2017
27. THINGS TO REMEMBER > Documentation is a must > Think twice let result = a &- b ||> c <^> d *> f © Dmitrii Celpan, mobOS 2017
28. THINGS TO REMEMBER > Documentation is a must > Think twice > Avoid complicated symbols © Dmitrii Celpan, mobOS 2017
29. THINGS TO REMEMBER > Documentation is a must > Think twice > Avoid complicated symbols > Don't overuse "?" © Dmitrii Celpan, mobOS 2017
30. THINGS TO REMEMBER > Documentation is a must > Think twice > Avoid complicated symbols > Don't overuse "?" > Be closer to the community © Dmitrii Celpan, mobOS 2017
31. USABILITY IS MORE IMPORTANT THAN BEAUTY © Dmitrii Celpan, mobOS 2017
32. > Custom Operators in Swift, http:// www.codingexplorer.com > Swift Operators, http://nshipster.com > Operators, Operators, Operators: Introducing Precedence, http://ericasadun.com > https://github.com/apple/swift-evolution/blob/ master/proposals/0077-operator-precedence.md © Dmitrii Celpan, mobOS 2017
33. > Argo, Functional JSON parsing library > Runes, Infix operators for monadic functions > Prelude, µframework of simple functional programming tools > Kickstarter, Open Sourced iOS app © Dmitrii Celpan, mobOS 2017
34. Q&A Thank you @DmitriiCelpan lexorus / celpand © Dmitrii Celpan, mobOS 2017